My guy asked me to cut a 1mm pitch thread on a custom shaft.
I could not do it on my lathe, so I finally bit the bullet and wrote a subroutine to do threading with my 4th axis rotary table. I use a 60 degree chamfering end mill.
Now I can cut any thread, any pitch, right or left handed, and if the thread is very coarse, the subroutine does it in several passes.
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I am afraid that it does not create a 100% correct thread geometry, but I hope that I can do enough things with it to be useful with some adjustments to diameter.
(Makes a thread on a round part rotated in my fourth axis) (Uses a 60 degree end mill)
O sub # = #1 (X0, left side) # = #2 (X1, right side) # = #3 (Y, middle of the top edge of the round) # = #4 (Z, top of the edge of the round) # = #5 (Safe Z for rapids) # = #6 (Z Step, positive) # = #7 (Step Per Revolution, Also determines Total Depth) # = #8 (Depth of thread, positive, determined automatically if 0 based on 60 degree thread.) # = #9 (Diameter of the round, needed for calculations of feed rate) # = #10 (feed rate based on surface speed) # = #11 (Set to 1 if left handed)
Nice - to bad you can't use a hob ? I think that what thread cutters are or Cob... They have cutters a foot long and 6" in diameter - coated and all - here in Lufkin - the foundry at Lufkin Industries has to do it all. Massive gears and massive bolts and nuts.
The traditional donkey that pumps out oil is twice as long as those made by Lufkin. Their custom way saves space and when in buildings (hiding the pump) it becomes important.
Mart> My guy asked me to cut a 1mm pitch thread on a custom shaft.
Yes, to do it properly, I would need to orient the rotary table at angle to axis X. Too difficult for me to do it. I will mess with making threads to see how geometry affects fit and how I can compensate by fudging the diameter.
twice now, the auctioneer has called them taps. Makes for a really good deal, I got one lot of 30 "taps" for $100. Even overheard one guy saying that guy was crazy bidding $100 on taps.
For a 1MM pitch, a hand ground, single point hss threading tool probably would have worked just as well and would also have produced the correct root geometry.
Unlike iggy, I'm not good at selling things. I do plan to have the best estate auction anybody has ever seen. I think, he who dies with the most toys, wins.
Converting a Bridgeport milling machine to Linux is also a skill.
And yapping on forums about "having access to a friend's shop" is not a skill.
As for single point threading, my current problem is that the spindle has to be on brake. However, spindle brake right now is tied to estop. It only activates when the mill is e-stopped, and deactivates when the mill is out of estop. Fixing that requires me to spend a considerable time writing emc2 logic statements (to interlock brake and estop and spindle running safely). I do not have time for this right now.
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